Experimental investigation of welded steel T-stub components under high loading rates

Abstract

The equivalent steel T-stub approach is widely used in practice to analyse and design bolted steel joints that are otherwise complex to study. The available analytical and empirical models for characterizing the response of T-stub components are based on numerous experimental and numerical research studies. This research is mostly concerned with the pseudo-static response of the T-stub. However, natural and man-made hazards (such as earthquakes and impacts) are dynamic. Considering the strain-rate sensitivity of steel, dynamic effects may have a notable effect on structural behaviour. A limited number of studies investigated the response of steel components/joints at high loading rates with inconclusive, and sometimes conflicting, observations. Accordingly, an experimental study is undertaken to address the data shortage. A total of 57 welded steel T-stubs were tested under monotonic tension. The main test parameters included the T-stub flange plate thickness, the loading rate, and the bolt preload condition. The test data underscored the influence of the loading rate and bolt preload. Notably, at a loading rate of 50 mm/s, an average of 35% reduction in the elastic stiffness, a 5% amplification of strength, and a 22% reduction in ductility is observed compared to the reference pseudo-static loading rate. The paper discusses the test observations in detail, evaluates the findings considering past research, and assesses potential implications on design.